gm82c765b ETC-unknow, gm82c765b Datasheet - Page 16

• Manufacturer Part Number: gm82c765b
• Description: Floppy Disk Subsystem Controller
• Manufacturer: ETC-unknow

TABLE 5. STATUS REGISTER 2 BITs
TABLE 6. STATUS REGISTER 3 BITs
Note :
D7
D6
D5
D4
D3
D2
D1
D0
#D3
D2
D1
D0
TABLE 4. STATUS REGISTER 1 BITs
NO
#D7
#D5 READY
NO
D0
NO
D6
D4
* *
* * *
#
*
MISSING
ADDRESS
MARK
CONTROL
MARK
DATA ERROR
WRONG
CYLINDER
SCAN EQUAL
SCAN NOT
BAD
CYLINDER
MISSING
ADDRES
MARK
IN DATA FIELD
TRACK 0
HEAD SELECT
UNIT SELECT 1
CYLINDER
UNIT SELECT 2
WRITE
PROTECTED
WRITE
PROTECTED
NAME
NAME
NAME
IDR
C
CRC - Cyclic Redundancy Check
BIT
BIT
BIT
- Cylinder
- Different from NEC765
- internal Data Register
SYMBOL
CM
DD
WC
SH
SN
BC
MD
SYMBOL
SYMBOL
MA
US1
US0
WP
WP
RY
TO
HS
If the FDC cannot detect the ID Address Mark after encountering the
index hole twice, then this flag is set.
If the FDC cannot detect the Data Address Mark or Deleted Data Address
Mark, this flag is set. At the same time the MD (Missing Address Mark in
data field) of Status Register 2 is set.
Not Used. This bit is always 0 (low)
During executing of the READ DATA or SCAN Command, if the FDC
encounters a sector which contains a Deleted Data Address Mark, this flag
is set.
If the FDC detects a CRC error in the data field, then this flag is set.
This bit is related to the ND bit, and when the contents of * * * C on the
medium is different from that stored in the IDR, this flag is set.
During execution of the SCAN command, if the condition of “equal” is
satisfied this flag is set.
During execution of the SCAN command, if the FDC cannot find a sector
on the cylinder which meets the condition, then this flag is set.
This bit is related to the ND bit, and when the contents of C on the
medium is different from that stored in the IDR, and the contents of C is
FF, then this flag is set.
When data is read from the medium, if the FDC cannot find a Data
Address Mark or Deleted data Address Mark, then this flag is set.
Not used. Will always be logic 0.
This bit is used to indicate the status of the WRITE
signal from the FDD
This bit will always be a logic 1.
Drive is presumed to be ready.
This bit is used to indicate the status of the Track 0 signal from the FDD.
This bit is used to indicate the status of the WRITE PROTECTED
signal from the FDD
This bit is used to indicate the status of the Side Select signal to the FDD
This bit is used to indicate the status of the Unit Select 1 signal to the
FDD
This bit is used to indicate the status of the Unit Select 0 signal to the
FDD
16
DESCRIPTION
DESCRIPTION
DESCRIPTION
GM82C765B
PROTECTED